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Amateur Radio
RF Environment Evaluation Exemption Calculator
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Optional Information
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Enter Frequency in MHz
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Calculated Minimum Distance Required (Feet)
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Enter
Distance to Antenna (Feet) Note: Minimun Distance 7.87"
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Calculated - Does Exemption Apply?
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Select Coax Type
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Enter Length of Coax in feet
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Enter Transmitter Power in Watts
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Select dBi or dBd and Enter Antenna Gain
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Calculated - Effective Radiated Power (ERP) (Watts)
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Calculated - Maximum Allowed ERP (Watts)
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The Amateur Radio RF Environment Exemption
Calculator determines if the FCC
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Exemption to Routine Evaluation applies. It also
calculates the maximum allowed
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Effective Radiated Power (ERP). Enter the frequency
and distance to the antenna.
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If the calculator indicates that the exemption
applies, select the type of coaxial cable,
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enter the cable length, transmitter power and
antenna gain. The calculator displays
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the station's ERP and the maxium allowed
power. Adjust transmitter power
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may be adjusted to keep the station's ERP below the
maximum allowed.
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Note: Stations, not qualifying for an exemption,
may still meet the FCC Maximum Permissible
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Exposure (MPE) limits by perfoming a RF
environmental analysis. A suggested
resource,
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with more information is: www.arrl.org/rf-exposure.
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Calculation formulas:
The exemption applies if, R, the distance between the antenna and human
exposure (meters) is greater than the wavelength/2π. The maximum allowed
ERP is determined by the adjacent formulas, where "f" is frequency
(MHz).
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Frequency (MHz)
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Maximum ERP (Watts)
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0.3 - 1.34
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1,920 * R^2
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1.34 - 30
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3,450 * R^2 / f^2
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30 - 300
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3.83 / R^2
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300 - 1,500
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0.0128 * R^2 *f
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1,500 - 100,000
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19.2 * R^2
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This calculator is being made available in support
of Amateur Radio activities.
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The author assumes no
liability or responsibilities for errors or omissions.
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Rev 3.7
Authored by KA6UGS. For
questions email: [email protected]
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